The invention is in the field of industrial processes for drying the solid residue of filtration processes.
Such filtration residues as dyes, pigments, metal hydroxides, catalysts and many others have generally been dried within the filter itself. The known processes for drying these residues on horizontal filter plates generally employ heated air or inert gases, which are passed through the filtrate inlet and dry the filtration residue in passing through the residue.
A disadvantage of this process is that the filtration residue has a tendency to cake up, making removal of the residue from the filter as well as transport of the residue out of the filtering tank difficult.
Similar results are found with the use of alluvial matting filter candles; however, the filter cakes tend to crack more readily as air is passed through the filter candles, and the air would tend to follow the path of least resistance through the filtration residue, minimizing the effectiveness of drying.
In the Swiss Pat. No. 569,503, a process has been disclosed in which the residue is homogenized within the filtration apparatus while still wet (i.e., before the passage of air through the residue to dry it). The drying process itself is performed elsewhere.